2009-09-12 04:00:00 PDT San Francisco -- Crews are investigating a power outage affecting approximately 34,460 Pacific Gas & Electric Co. customers in several San Francisco neighborhoods this morning, a utility spokeswoman said.

The outage began at around 5:15 a.m. and is disrupting power in the Sunset, Parkside, Outer Mission, Laurel Heights, St. Francis Woods, Glen Park and Excelsior neighborhoods, PG&E spokeswoman Brandi Ehlers said.

The cause of the outage has not been determined, Ehlers said.

The utility company hopes to restore power as soon as possible, though no estimated time of restoration was available as of 6 a.m